Previously known cylinder-lock attachment means of this kind are normally designed to be mounted on the inside of a door, and to this end are designed to fit into a standard-size hole made in the door for this purpose, the diameter of the hole in the case of Swedish standards being 40 mm.
The headed screws are passed through the cylinder lock and are normally screwed into a corresponding cylinder lock on the outside of the door, in which case the screws are passed through a lock housing arranged in a recess in the door and accommodating a lock mechanism, normally a latch plunger mechanism, which can be activated by the cylinder locks.
The escutcheons or cylinder fittings may also be mutually connected together by means of one or more screws, which then also pass through the lock housing.
Thus, the cylinder lock located on the outside of the door is joined to the cylinder lock on the inside of the door by means of screws whose heads are located in the "inner" lock and which cannot therefore be reached from the outside of the door. The screw-heads, however, can be reached from the inside of the door, and tightening of the screws with a screw driver causes the two cylinder locks to be urged towards each other while being accurately fixed and aligned relative to each other and to the door.
An arrangement of this kind creates problems when the door in question cannot be considered to have an inside and an outside, i.e. both sides of the door can be considered as the "outside". This is primarily the case with locales and rooms which have additional entrance possibilities. In this case it is relatively simple for a person to unlawfully activate the "inner" cylinder lock, by simply unscrewing the readily accessible screws, removing the cylinder lock and then releasing the latch plunger mechanism in the lock housing, in a suitable manner.
Normal houses and flats present a similar problem, particularly if an intruder is able to gain entrance through a readily forced balcony door, a lower floor window or the like, whereafter the cylinder lock on the "inside " of a door can readily be opened in the aforesaid manner, enabling the intruder to leave through a conventional exit, normally the main front door, together with any stolen goods. It will readily be understood that much less attention will be paid to an intruder who uses a normal exit as his retreat path, and that he or she will be more difficult to discover than if leaving the building, together with any stolen goods, via a lower floor window, balcony door or the like.